Distillation is used to obtain pure water that has no impurities dissolved in it. The pH of freshly distilled water is 7.0 at 25 °C. This value decreases as temperature increase (6.2 at 100 °C) and increases as temperature decrease (7.5 at 0 °C). It depends on the ionization constant of water (Kw) which is affected by temperature.
After distillation of water (during storage) its pH could change. Carbon dioxide (CO2) from the atmosphere dissolves in water to produce carbonic acid which reduces the pH. In addition, if water is stored in some types of glass containers then alkali material could leach from the glass and increase the pH. That is why it is important to have freshly distilled water to eliminate any possible impurities.
After distillation of water (during storage) its pH could change. Carbon dioxide (CO2) from the atmosphere dissolves in water to produce carbonic acid which reduces the pH. In addition, if water is stored in some types of glass containers then alkali material could leach from the glass and increase the pH. That is why it is important to have freshly distilled water to eliminate any possible impurities.
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